Thea Beatrice May Astley was born in Brisbane in 1925. She attended All Hallows, a Catholic school in Fortitude Valley, before studying arts at the University of Queensland. Astley trained to be a teacher and, on marrying Jack Gregson in 1948, moved to Sydney and worked in a number of schools. The pair had a son, Ed. In 1958 Astley's first novel, Girl with a Monkey , was published. Over the next four decades she published a work of fiction every few years. Her novels and short stories are distinguished by vivid imagery and metaphor; a complex, ironic style; and a desire to highlight oppression and social injustice. Astley won the Miles Franklin Literary Award for The Well Dressed Explorer (1962), her third novel.

Many notable books followed, among them the groundbreaking A Kindness Cup (1974), which addressed frontier massacres of Indigenous Australians, and It's Raining in Mango (1987). In the late 1960s Astley took up a position at Macquarie University, where she worked until 1980, when she began to write full-time. She and Gregson moved to North Queensland, returning to New South Wales later that decade. Astley won the 1989 Patrick White Award and became an Officer in the Order of Australia in 1992. Her last novel was Drylands (1999), her fourth Miles Franklin winner and first since 1972. A lifelong chain-smoker famed for her sharp wit, Thea Astley died in 2004, the year after her husband died. She remains one of the most distinctive and influential Australian novelists of the twentieth century.